Optoelectronic property tuning of A2BX6(A = In, tl; B = Pd, pt; X = Cl, Br, I): A first-principles study

The structural stability, energy band and photoelectric properties of vacancy- ordered double halide perovskites A2BX6(A = In, Tl; B = Pd, Pt; X = Cl, Br, I) are studied in detail by first principles in this paper. The results show that these materials have suitable tolerance factor, negative formation energy and good phonon spectrum, which indicates that they have structural stability. These materials are all semiconductors with band gaps varying from 0.328 eV and 3.238 eV via HSE06 hybrid functional. All the materials have direct or quasi-direct band structures, which are beneficial for carrier generation. These materials have small reflectance and large absorption coefficients for visible - infrared light, especially in the ultraviolet region where the absorption coefficient is very large. The absorption coefficient of the material is obviously improved when the anion X changes from Cl to Br to I. Making a comprehensive analysis of absorption coefficient, transmittance and bandgap values, Tl2PdBr6 is regarded as a potential candidate for solar absorber in single junction solar cells, while In2PtCl6 and Tl2PtCl6 may be applied in transparent conductor films.